A number of injector-actuated syringes and powered injectors for use in medical procedures such as angiography, computed tomography, ultrasound and NMR/MRI have been developed. U.S. Pat. No. 4,006,736, for example, discloses an injector and syringe for injecting fluid into the vascular system of a human being or an animal. Typically, such injectors comprise drive members such as pistons that connect to a syringe plunger. For example, U.S. Pat. No. 4,677,980, discloses an angiographic injector and syringe wherein the drive member of the injector can be connected to, or disconnected from, the syringe plunger at any point along the travel path of the plunger via a releasable mechanism. A front-loading syringe and injector system is also disclosed in U.S. Pat. No. 5,383,858.
U.S. Pat. No. 5,494,036 discloses a patient infusion system adapted for use in MRI. The infusion system is designed to be substantially non-reactive with the magnetic field generated by the magnetic resonance imaging system for producing diagnostic images.
Medrad has also developed a control arrangement (“SPECTRIS”) for an MRI infusion system that uses two syringes, namely, one for the introduction of contrast medium into a patient and the other for a flushing medium. As is known conventionally, it is often desirable to flush from the tubing of an infusion system a residual quantity of contrast medium that remains there after a given infusion procedure, as contrast medium tends to be expensive and its efficient use, without waste, is often seen as a top priority. The “SPECTRIS” control arrangement will thus not only account for the residual contrast medium left in the tubing, and aim to use it in an infusion procedure, but will utilize a much cheaper flushing medium, such as a saline solution, in order to serve the purpose of pushing the residual contrast medium through the tubing and even through the patent's body (so as to “push” and deliver contrast medium to a region of interest in the body). Other advantageous purposes have also been recognized in connection with such flushing media, such as maintaining a flow through the patient's veins for a predetermined period of time in order that the veins will be better prepared to subsequently receive a new infusion of contrast medium.
The “SPECTRIS” control arrangement is a pre-programmable arrangement for establishing a precise protocol for the infusion of contrast medium followed by flushing medium. At the time that the “SPECTRIS” system was established, needs in the industry were generally such that only some very simple protocols were desired. Thus, the “SPECTRIS” system addressed such needs by permitting protocols in which one or two “phases” of contrast medium took place followed by zero, one or two “phases” of flushing medium infusion. “Phase” refers to the application of a given quantity of a given medium at, for example, a fixed flowrate for a fixed period of time. Thus, up to two phases each of contrast medium and flushing medium, for example, were permitted by the “SPECTRIS” system, in order to provide a patient with different modes of infusion one after the other to serve particular purposes.
Of late, however, some disadvantages have been noted in connection with the “SPECTRIS” control system and other related systems. Not the least of these is the lack of flexibility in developing and administering infusion protocols to a patient, as the “SPECTRIS” system would allow no more than two distinct phases for each medium, and no single phase of flushing medium infusion could take place between two different phases of contrast medium infusion.
A further disadvantage has been recognized in that the aforementioned phases will typically be administered one after the other without the opportunity for an intermediate pause or hold between phases. This would appear to limit the convenience and utility of the system in question in many respects.
Nemoto and Co., Ltd., of Tokyo, Japan has also developed a control system for an MR injector. However, this appears to be even less flexible than the “SPECTRIS” system in that only protocols consisting of no more than one contrast medium infusion and no more than one flushing medium infusion appear to be permitted.
In the realm of CT (computed tomography) injection technology, Medrad has developed the “ENVISION” control system. As flushing media have generally not been hitherto employed in CT injector systems, the “ENVISION” system, much as any conventional CT injector control system, contemplates only the use of a single syringe for patient infusion, and solely for use with contrast medium. The “ENVISION” system permits protocols that employ up to eight different phases of contrast medium infusion, wherein each phase may employ a different infusion flowrate, infusion quantity and/or infusion duration. Pre-programmed pauses between infusion phases are also conceivable within such a context.
Evolving needs have thus been recognized in connection with providing an injection control system that is much more readily adaptable to a wider range of contexts.